PT-2026-64519 · Linux · Linux
CVE-2026-64298
·
Published
2026-07-25
·
Updated
2026-07-25
None
No severity ratings or metrics are available. When they are, we'll update the corresponding info on the page.
In the Linux kernel, the following vulnerability has been resolved:
NFSv4: include MAY WRITE in open permission mask for O TRUNC
POSIX requires write permission to truncate a file, so an open() that
specifies O TRUNC must be authorized for write access regardless of the
O ACCMODE access mode.
nfs open permission mask() builds the access mask passed to
nfs may open(), which is the local authorization gate for OPENs the
client serves itself from a cached write delegation via the
can open delegated() path in nfs4 try open cached(). The mask is
derived from O ACCMODE alone, so an open(O RDONLY | O TRUNC) against a
file the caller cannot write requests only MAY READ and passes the
local check. The OPEN is then satisfied locally and the truncation is
issued to the server as a SETATTR(size=0) over the delegation stateid,
which the server accepts under standard write-delegation semantics.
POSIX requires that this open fail with EACCES.
Include MAY WRITE in the mask whenever O TRUNC is set so the local
check matches the access the server would have enforced.
Found an issue in the description? Have something to add? Feel free to write us 👾
Related Identifiers
Affected Products
Linux